Such brushes are used, in particular, for applying mascara to the eyelashes or dye to the hair.
FR-A-2,607,373 shows a brush of this type, a variant embodiment of which includes bristles having a cruciform cross-section. Four reserves of make-up product are thus constituted along each bristle. At the time of application, the reserves of product are progressively emptied and lead to a homogeneous and thick coating of the eyelashes.
Although permitting an improvement in making-up, such a brush has a certain overall hardness which may sometimes lead to irritation of the skin of the eyelids. The symmetry of the transverse section of the bristle, with respect to the center of this section, gives rise to virtually identical behavior on the part of all the bristles when they are squashed in the zone of twisting of the metal core so that the ends of the bristles reproduce the spiral effect created by the twisted core.
U.S. Pat. No. 3,121,040 relates to filaments made from polyolefins which are used in different types of brushes. Various sectional shapes, presented as equivalents, are proposed for improving the resistance of the filaments to deformation. Among these sectional shapes is a V-shaped section or a substantially L-shaped section, with no other particular indication which might lead to this shape being adopted in preference to the others.